Hundreds of people turned up one Sunday this month to say their last good-byes to Huang Na, an eight-year-old girl from China who had been studying at a school in Singapore. Her disappearance on October 10 sparked a citywide search. Unfortunately, her body was discovered 20 days later in a tightly sealed cardboard carton, hidden among thick undergrowth at the bottom of a steep slope. Her alleged murderer, a 23 year-old Malaysian worker, was a friend of her mother's. This sad incident sends a sombre reminder that no matter how independent and resourceful our children may be, they are still highly vulnerable. Keeping a vigilant eye on them has never been more crucial. This probably explains why home-monitoring services and security webcams have become popular. Many parents have also equipped their children with mobile phones to keep tabs on where they are and who they are with. The belief is that they can easily contact a parent if they ever get into an emergency. But there is no point if they cannot describe where they are. This is where global positioning system (GPS) technology comes in. It is a worldwide satellite-based navigation system that uses the beam signals from 24 orbiting satellites, allowing people to locate a registered device within several metres. Unfortunately, today's many GSM/GPRS mobile phones do not have GPS functionality. And while mobile operators can locate a phone's signal through its base stations, they are not as accurate as GPS. The good news is more handsets with GPS functionality are starting to appear, led by 3G handset manufacturers and GPS device makers such as Garmin. The bad news is that such phones are priced beyond affordability (although one could argue that, when it comes to protecting your loved ones, cost should not be an issue). Many GPS-related services are geared for finding the nearest restaurant or movie theatre, rather than a lost child. Hutchison's 3, for example, offers a location service showing your location on a map in relation to your destination. It lets you know if your friends are nearby, but it is not linked to any emergency service. What we really need are cheap, basic phones with a GPS receiver so children are not burdened with the responsibility of carrying around a full-featured, high-end handset. In any case, fancy mobiles are a big distraction, and a magnet for misuse. Colour screens, stereo sound and Java games are considered cool, but not welcome in the classroom. Some schools already ban mobile phones since they do so much more than allow you to talk or text. It is an electronic gadget, a toy. Should your child ask you for a mobile phone, chances are it is not for emergency purposes. Mobile handsets have become part status symbol, part fashion accessory, and all but necessary if you want to be popular. As a father of three young children, I do not buy that. What I would suggest is to give them your old phone, and tell them that the phone belongs to you, not them. Ownership is everything. They're simply 'borrowing' your phone, so that means they'll have to be extra careful. If you have to buy a new phone, save some money and get an entry-level handset. Plus, it won't hurt as much if it gets lost or stolen. You may want to consider a subscription plan as it will be far easier to track the calls your children are making, how many messages they are sending and the kind of content they're downloading. Mobile operators may disagree, but data downloads such as ring tones and wallpaper are still relatively expensive compared with the typical amount of pocket money children receive. Prepaid cards are much harder to track and would afford you less control over how the phone is used. With a monthly mobile bill, you'll be able to better manage the usage. There is another way. Trust your child with the task of handling the phone responsibly by setting limits that have been agreed on. Let him or her understand that the handset isn't for showing off to friends but to ensure you are available any time, any day, and that you'll be there for them in a time of need. For now, though, this is a stop-gap solution. Governments and the telecommunications industry need to work together to quickly and cheaply bring on GPS-based emergency services so children have a much better chance of survival when they go missing. Keith Liu is the anchor and correspondent of CNBC Hong Kong's technology programmes e and Generation-e.